Bioliquids: do they have a role in renewable energy?

Bioliquid uptake between now and 2020 is likely to be "modest", according to a new report by the UK’s National Centre for Biorenewable Energy, Fuels and Materials.

But just what is holding back the industry? Uncertainties regarding bioliquid availability – as well as sustainability, planning and financial issues – are the main culprits, says the report.

Burning bioliquids, such as virgin or waste vegetable oils, to generate heat and electricity, has been a hot topic recently. Bioliquids include feedstocks like palm and soy oil, which are seen by some as controversial.

Controversy
The recent approval of a new bioliquids power plant near Bristol (UK) sparked several hundred complaints, following concerns over where the bioliquids would come from. But operators of the plant, W4B, have said they are committed to independent monitoring of the fuel sources to ensure they are 100 per cent sustainable.

So why are we interested in bioliquids? Their unique characteristics mean they are an attractive option for small-scale energy generation and often fill a niche where other renewable technologies are just not viable.
Advantages
For example, bioliquids have a higher energy density than most solid biomass fuels. This means bioliquids need smaller storage spaces than solid fuels, to produce the same amount of energy. It is also easier and cheaper to transport liquid fuels than solid fuels as they can be pumped and transported by tanker.

Burning liquid fuels is a well established technology and one which can be used on demand, reacting quickly to changes in demand for power. This key attribute of bioliquids means it is one of the few renewable energy technologies that can be used to balance out demand and supply levels on the national electricity grid, which is usually done by fossil oil or natural gas.

"Bioliquids have potential but can and must come from sustainable sources," says Fiona McDermott, lead author of the NNFCC report.

"Support should be given to bioliquid applications which offer good greenhouse gas savings, a technologically effective solution to onsite generation needs, and fill the gap where other renewable technologies are not viable."

The report finds that so long as bioliquids come from sustainable sources that offer a good carbon footprint, they will have a role to play in helping the UK meet its renewable energy targets.

Obstacles
But there are still significant obstacles in the way before bioliquids can fulfil their potential; these include uncertainty over fuel costs, current policy framework, infancy of the supply chain and public concerns.

As a result, the NNFCC report predicts that uptake of bioliquids is likely to be low between now and 2020. Under a low uptake scenario bioliquids could generate four per cent of the Renewable Energy Strategy 2020 target for renewable electricity and six per cent of the target for renewable heat.

The findings of the report are now being used in the banding review of the Renewables Obligation being carried out by the Department of Energy and Climate Change.

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